DE3121787A1 - Drying method and device - Google Patents

Description

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GENERAL ELECTRIC COMPANY

1 River Road Schenectady, N.Y./U.S.A.

description

The invention relates generally to a method and a device for drying, and in particular to a drying method and a drying device in which a drying fluid dehumidifies and is circulated.

In most drying processes, a volatile Liquid expelled from an object of interest by allowing the object to evaporate Supplies sufficient heat to the liquid. This heat is often applied by means of a drying fluid such as by means of hot air, which is circulated in contact with the object in a drying chamber. The resulting vaporized liquid is admixed with the drying fluid and out of the drying chamber sucked off. For reasons of simple training as well as the earlier low energy costs, the The effluent mixture of drying fluid and steam is typically simply vented to the atmosphere. A household tumble dryer is an example of this type of drying. However, this type of drying is used the heat of vaporization that is added to the system, used uneconomically.

In particular, it should be said that most of the heat of evaporation which is supplied to a drying process, as latent

Heat by condensing the evaporated liquid before this is blown out of the system can be recovered. In certain use cases, such as when drying wood, the use of a vapor compression heat pump in a drying process has been suggested to allow the available latent heat to be recovered. In such a system becomes latent Heat from a vaporized fluid that has been removed from a drying chamber by condensation recovered in a heat pump evaporator. The ^ recovered latent heat is then used in the heat pump condenser delivered to drying fluid that is fed into the Enters drying chamber.

Although drying process with ■

Such methods are used to enable heat pumps to recover latent heat effectively limited in scope. For example, the high capital costs associated with heat pump coupled drying facilities are connected, the latter unacceptable for many applications. Heat pump-coupled ones are accordingly Dryers are often prone to heat exchanger fouling, as in certain drying applications of clothing.

Accordingly, the present invention aims to provide a new and there is provided an improved method and new and improved apparatus for drying.

In addition, with the present invention, a new and improved method and new and improved apparatus for drying are provided in US Pat which latent heat of vaporization is effectively recovered.

Finally, with the present invention, an effective

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The same drying process and an effective drying facility which are low cost and operable at low cost, and at which avoid the need for heat exchangers and which also have a wide range of applications are customizable.

Briefly summarized are the foregoing and other advantages and features of the invention with a drying process achieved in which liquid is continuously extracted as vapor from an object by the object is brought into contact in a drying chamber with a drying fluid that is added to the chamber is supplied to a temperature which is above the liquid evaporation temperature lies. The extracted steam is in an effluent mixture with the supplied Removed drying fluid from the chamber. The outflowing Drying fluid is then recirculated to the drying chamber by removing the effluent Mixture is first accelerated enough so that the condensation of at least a portion of the extracted Steam is effected. The condensed vapor is then removed from the effluent mixture in a liquid extractor removed, and the resulting effluent mixture is fed to a compressor in which the The temperature and pressure of this mixture is increased before it is returned to the drying chamber. In embodiments the present invention, which are described below, is a portion of the effluent mixture, which has been removed from the drying chamber is discharged from the process before the remaining mixture flowing out is accelerated. Accordingly, an amount of replacement or fresh drying fluid and additional Heat to the recirculated drying fluid during the recycle of the fluid

can be added to the drying chamber. A device for carrying out this method is also described.

For a better understanding of the invention, this is the following based on a particularly preferred embodiment below Referring to the figure, explained in more detail, which is a schematic representation of an exemplary or particularly shows preferred device for drying clothes, which according to an embodiment of the present Invention is constructed.

A drying device according to the present invention, as shown in the figure, for example, for the application of the Drying clothes is shown, has a drying chamber 1, which is provided with a heated drying fluid, such as air, is fed through an inlet 2. In a drying process, a outflowing mixture of drying fluid and evaporated liquid withdrawn through an outlet 3 from the drying chamber. The outflowing mixture is in a circulation process before they pass through the inlet 2 into the Drying chamber 1 is returned, dehumidified, heated and pressurized.

The drying chamber 1 shown here has an outer structure 4 which is designed to have drying fluid the items to be dried, such as the items of clothing shown at 5, directs. In order to optimize the use of the drying fluid, the outer structure 4 is preferred constructed so that it is substantially sealed during operation of the device. As shown are the garments 5 contained in a foraminous rotatable drum 6 which is typical of most conventional clothes drying devices and is therefore

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tends to facilitate the heating of the garments by the drying fluid. The outlet 3 is positioned through the outer structure 4 so as to facilitate the removal of the effluent mixture of drying fluid and evaporated liquid from the drying chamber 1 allows.

A fluid accelerator 7 is like that connected that it receives the flowing mixture from outlet 3 and accelerates the same enough so that the steam is condensed in the mixture. Specifically, the mixture flowing out becomes continuous in the fluid accelerator 7 accelerates the condensation of the vapor by converting the latent To effect thermal energy in kinetic energy. As shown in the figure, the flow center includes accelerating means advantageously a converging nozzle which has a very rapidly converging section 8 has, in which the flowing mixture quickly up to the vicinity of the condensation conditions or the condensation state is accelerated. The nozzle contour then merges into a relatively slowly converging section 9, in which reduces the rate of acceleration of the mixture while the vapor is being condensed. In this way the steam is effectively condensed while minimizing the thermodynamic imbalance that with the application of high speed in the vicinity of the dew point conditions or the dew point state of a fluid is connected, whereby typically the dew point with reference to the equilibrium conditions or the state of equilibrium is depressed.

Both sections, namely sections 8 and 9, of the converging Nozzles are also contoured to minimize frictional energy losses therein.

so that circulatory efficiency is maximized. Accordingly, the nozzle sections are advantageously designed so that the formation of shear forces is avoided which might otherwise act to reduce the condensate droplet size. In this way is collecting the condensate by the droplet size depends, improved.

To speed up the outflowing mixture to a for For condensation to occur, the nozzle section 9 must have a predetermined minimum cross-sectional flow area for a given pressure drop at or above the nozzle. However, it is necessary The rate of condensation is also a function of the vapor being condensed. For the application shown in Fig. 1, in which the outflowing mixture contains air and water vapor, the necessary condensation rate is at least about 0.5 Mach, and it is preferably between at least about 0.65 Mach and about 0.9 Mach. The minimum nozzle cross-sectional flow area is correspondingly for such an application

2 preferably between about 0.32 cm (0.05 square inches) and

2
about 3.2 cm (0.5 square inches). Within this range, the flow area can be increased to allow a greater flow rate or decreased to allow more complete condensation of the steam.

The fluid accelerator 7 is at its outlet with a liquid extractor connected, in which condensed vapor is removed from the effluent mixture. The one shown in FIG Liquid extraction device 1o is an inertial separation device, in the centrifugal forces to separate the relatively heavy condensed vapor from the auaatrümundun Mixture can be used, although the liquid extract

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tion device 1o does not rely on such an embodiment is limited. In the embodiment of FIG. 1 leads accordingly the inlet of the inertial separator to a bifurcated section in which a first conduit is substantially continues straight forward to a first extracted liquid outlet 11. A second line branches off from the first in a controlled curved manner and leads to a second outlet 12 for the remainder the outflowing mixture that flows into the device 1o. A suitable trigger device 13 is at the outlet 11 for the extracted liquid is provided to collect the condensed vapor and remove it from the system without interrupt the inertial separation process by a large pressure drop.

It is advantageous if the liquid extraction device Io to a complete condensate extraction in the It is possible that any moisture contained in the mixture evacuated through outlet 12 is subsequently must be compressed, which leads to an unnecessary amount of work, without an equivalent compensating drying effect is achieved when the mixture is returned to the drying chamber 1. However, the entire requires Extraction of the condensed vapor typically adds additional compressor work, which outweighs any benefits achieved can. As a result, while complete liquid extraction is often desirable, it is for the Not necessary to practice the present invention.

The resulting dehumidified effluent mixture passed through the second outlet 12 of the liquid extractor 1o has been discharged, is used as drying fluid for drying chamber 1 after suitable compression returned. Accordingly, the outlet 12 is in fluid communication with a compressor device 14. As shown

set, the compressor device 14 has a centrifugal compressor 15 driven by a motor 16, which has a diffuser inlet and outlet 17 and 18, respectively. The compressor device 14 is dimensioned in a suitable manner so- sen that they the sucked through the outlet 12 fluid heated and its pressure increased to the existing or required pressure in the drying chamber 1. The compressor outlet 18 is in flow communication with inlet 2 of the drying chamber, thereby enabling the drying fluid cycle process is completed.

In a preferred embodiment of the present invention, an outlet air port 19 is in fluid communication with the flow path of the outflowing mixture between the outlet 3 of the drying chamber and the inlet the fluid accelerator 7 provided. A device 20, such as an inlet air port, is also in fluid communication with the inlet 2 of the drying chamber for supplying additive or fresh drying fluid provided in the same. In addition, a heating device 21, such as the Resistance heater shown in Figure 1, advantageously in thermal contact with the drying fluid be provided which flows from the outlet of the compressor device 14 to the inlet 2 of the drying chamber.

In operation, there is heated drying fluid such as for example air, through the inlet 2 into the drying chamber 1 and is here in contact with to be dried Objects such as B. garments 5 brought. This process gives the garments enough warmth supplied to cause evaporation of at least a portion of the liquid contained therein. The received Steam is mixed with the drying flow medium and as an outflowing mixture through outlet 3 of the drying

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suction chamber sucked off.

The outflowing mixture is accelerated by the fluid accelerator 7 accelerated in a suitable manner in such a way that enough thermal energy is converted into kinetic energy is converted so that the condensation of at least a part of that contained in the effluent mixture evaporated Liquid is effected. Preferably, all of the vaporized liquid is accelerated in this process condensed.

The resulting effluent mixture containing the drying fluid which has been introduced through the inlet 2 into the drying chamber, and that in the Fluid accelerator 7 condensed vapors are supplied to the liquid extractor 1o. In the device 1o condensed steam is extracted from the resulting mixture, for example by Centrifugal force. The extracted liquid is in the Deduction 13 collected and discharged from the process.

The dehumidified effluent mixture obtained is fed to the compressor device 14 through the outlet 12. That Fluid entering the compressor device 14 is preferably free of vaporized liquid and of Condensate. However, it may contain some of these components depending on design considerations underlying the system, as indicated above. The compressor device 14 generates a sufficient vacuum at inlet 17 such that this allows the fluid to flow from the drying chamber 1 through the fluid accelerator 7 and effected in the compressor device 14. The in the compressor device 14 incoming fluid is heated in this and used to return the fluid to the drying chamber 1

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pressurized enough.

Although sufficient heat is typically added or supplied in the device 14 during the compression process additional heat can be added to the drying fluid through the operation of the additional heater 21 will. Typically, this device is optionally used to reduce the drying rate within of chamber 1 or the rapid achievement of equilibrium conditions during initial operation of the system.

The air openings 19 and 2o are similar

provided so that an additional lip temperature control or control of the drying fluid is enabled. In this way, the moist mixture flowing out can pass through the outlet air opening 19 can be withdrawn before doing so any work is being done. Relatively cool dehumidified make-up or freshening fluid, such as for example air, is then supplied through the inlet air port 2o to allow a decrease in the temperature of the drying fluid, that enters the drying chamber 1 to effect.

As an example, that the drying chamber 1 is maintained at atmospheric pressure, in an exemplary embodiment of a drying device for garments, while the maximum temperature of the garments at 62 ⁰ C (144 ° F) is limited is provided. The system is designed for a drying rate capable of extracting 0.12 pounds of water per minute. This example assumes that 10% of the drying fluid is continuously vented and subsequently replaced during the process. The fluid accelerator

7 is a converging nozzle that has minimal transverse

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has an sectional flow area of 2 cm (o / 315 square inches) and is effective to accelerate the effluent fluid mixture entering the nozzle to a Mach number of approximately 0.86. Average efficiencies for the compressor device 14 (o, 6) and for the fluid extraction device 10 (o, 75) are taken as a basis, together with typical parasitic losses and a required power of 400 W.

As a result, what is required is a garment drying apparatus according to the present invention designed in this way Invention uses approximately 4039 kJoules (3830 BTU) of energy to produce a 3.2 kg (7 pound) load of clothing to dry from about 70% residual liquid to about 4%. In contrast, requires a conventional garment drying equipment typically produces approximately 7276 kJoules (69oo BTU) Carrying out an equivalent drying function or an equivalent drying process.

Of course, the invention is not restricted to the exemplary embodiments described and illustrated, but it can be within the scope of the subject matter of the invention and the general inventive concept in change with success in a variety of ways.

Claims (16)

Claims 1.J Drying process in which liquid is continuously LCh is extracted from an object as vapor by placing the object in a drying chamber with a drying flow fluid is brought into contact which is fed to the inlet of this chamber at a temperature which is above the liquid evaporation temperature, and in - by having the steam in an outflowing mixture the drying fluid is removed from this chamber and by further recirculating the drying fluid in the effluent mixture to the drying chamber is returned, characterized by the following process steps: (a) Directing the effluent mixture to a flow accelerator (7); (b) Accelerating the mixture flowing out in the flow accelerating device (7) to condense at least a portion of the steam; • A "2 ■ * ■" ** ** ··· (c) directing the effluent mixture from the flow accelerator (7) to a liquid extraction device (1o); (d) extracting condensed vapor from of the mixture flowing out in the liquid extraction device (1o); (e) conveying the resulting effluent mixture from the liquid extraction device (1o) to a compressor device (14); (f) increasing temperature and pressure the resulting outflow mixture in the compressor device (14); and (g) recycling the resulting effluent mixture from the compressor device (14) to the inlet (2) of the drying chamber (1). 2. Drying method according to claim 1, characterized characterized in that the outflowing mixture in dex flow acceleration device (7) a speed of at least 0.5 Mach is accelerated. 3. Drying method according to claim 1, characterized in that the outflowing mixture in the flow _{acceleration device (7) is accelerated to a speed of at least about o f} 65 Mach to about o, 9 Mach. 4. Drying method according to claim 1, 2 or 3, characterized in that the obtained outflowing mixture during the return of this mixture from the compressor device (14) to the inlet (2) the drying chamber (1) additional heat is added or supplied. 5. Drying method according to one of claims 1 to 4, characterized in that a Amount of mixture flowing out of the drying process . before the rest of the outflowing mixture is accelerated in the middle of the flow! (7) is removed. 6. Drying method according to one of claims 1 to 5, characterized in that an amount of additive or fresh drying fluid is added ^ is added to the resulting effluent mixture, while this mixture is returned to the inlet (2) of the drying chamber (1). 7. Drying method according to one of claims 1 to 6, characterized in that substantially all of the steam in the outflowing mixture is contained while being accelerated is condensed in the fluid accelerating device (7) will. 8. Drying method according to one of claims 1 to 7, characterized in that essentially all vapor condensed in the fluid accelerator (7) in the liquid extractor (1o) extracted from the effluent mixture and removed from the drying process will. 9. Drying device, in particular for performing the method according to one of claims 1 to 8, which has a Has drying chamber which has an inlet and an outlet, characterized by: a fluid accelerator (7) for accelerating a fluid having an inlet, * ft « • ο fr tt « ·· · ♦ which is in flow communication with the outlet (3) of the drying chamber (1) stands; a liquid extractor for extracting liquid from a fluid mixture (1o) in fluid communication with an outlet of the fluid accelerator (7) and a first outlet (11) for liquid that has been extracted from an inflowing fluid mixture, and a second Outlet (12) for at least a portion of the remainder of the inflowed mixture; a drainage device (13) with the first outlet (11) of the liquid extraction device (1o) is connected; and compressor means (14) having an inlet (17) in fluid communication with the second outlet (12) of the liquid extraction device (1o) is, and which has an outlet (18), which is arranged in flow connection with the inlet (3) of the drying chamber (1). 10.. Drying device according to claim 9, characterized characterized in that the flow center! (7) a converging nozzle (8, 9). 11. Drying device according to claim 9 _T, characterized in that the fluid acceleration device (7) has a converging nozzle (8, 9) which has a minimal cross-sectional 2 has a flow area which is between about 0.32 cm (o, o5 2
Square inches) and about 3.2 cm (0.5 square inches). 12. Drying device according to claim 9, 1o or 11, characterized in that the liquid extractor (11) is an inertial separation device embraces is desolate. 13. Drying device according to one of claims 9 to 12, characterized in that that the drying chamber (1) is essentially tight. 14. Drying device according to one of claims 9 to 13, characterized in that that it has an outlet air opening (19) which is in the flow connection between the outlet (3) of the drying chamber (1) and the inlet of the fluid accelerator (7) is arranged. 15. Drying device according to one of claims 9 to 14, characterized by a Device (2o) for supplying additional or fresh drying fluid which is in flow connection is arranged with the inlet (2) of the drying chamber (1). 16. Drying device according to one of claims 9 to 15, characterized by a heating device (21) which is in thermal contact with a Flow path is provided which extends between the outlet (18) of the compressor device (14) and the Linlaß (2) the drying chamber (1) is located so that the heating of the fluid flowing between them, is made possible.